<html window-frame="extended" 
      window-blurbehind="dark" 
      theme="dark"
      window-width="50%"
      window-height="50%">
    <head>
        <title>Test</title>
        <style src="extended-window-crome.css" />

        <style>
          body { background: rgba(0,0,0,0.7); color: #fff; margin:3px;}
        </style>
        <script></script>
    </head>

    <window-header>
      <window-icon role="window-icon" />
      <window-caption role=window-caption>Extended window</window-caption>
      <window-buttons>
        <window-button role="window-minimize"></window-button>
        <window-button role="window-maximize"></window-button>
        <window-button role="window-close"></window-button>
      </window-buttons>
    </window-header>

    <body>

window-frame="extended"


    </body>
</html>